Experimental approaches to generate compositional gradients in the fully biodegradable polymer blend system based on poly(3-hydroxybutyric acid)

The fully biodegradable polymer blend films compositional gradients from th e surface to the of the films were prepared by the solution-diffuse que. A solution of bacterial poly(3-hydroxybutyric acid) (PHB) in hexafluoro-2-pro panol (HFIP), which is good solvent for poly(vinyl alcohol) (PVA), was on a PVA film and the solvent HFIP was evaporated.By controlling the solvent ev aporation rate, the PHB/PVA blend film with a compositional gradient was ob tained. The phase structure and biodegradation profile of the PHB/PVA blend film were found to be different from those of the corresponding blend film prepared by the conventional solution-cast method.